Neutering will probably lessen but may not do away with it totally. However, leaving him intact will possibly allow the behavior to worsen over time. He's actually at about the ideal age to have it done. Fully grown but young enough to still be flexible. Age will affect his activity level more than neutering as long as you don't let him get fat. I don't think you can totally train it out of him either. I have a male aggressive dog (Shortybull) and it's a pain. Taking him out in public anywhere is no fun at all and he only weighs about 30 pounds. If he was an EB it would be close to impossible.